POPULATION-GENETICS OF SPINAL MUSCULAR-AT ROPHY

A population genetic study of spinal amyotrophy (SMA) in six Russian a nd three Cent-al Asian regions was carried out. In total, 29 patients with autosomal recessive (AR) infantile proximal SMA (SMA I-III) and f our patients with rare SMA forms with an unspecified type of inheritan ce were revealed. In Russian populations, the prevalence of SMA I-III is similar (1.5-2.5/100 000), it is one of the most common hereditary neurological diseases. A tendency toward nonuniform territorial SMA pr evalence is observed in genetically subdivided populations. The lesser SMA I-III prevalence in Central Asian populations might be due in par t to inbreeding depression. A segregation frequency of 0.21 is in acco rdance with AR inheritance; the proportion of sporadic cases is 3%. Cl inical genealogical data support the genetic unity df forms I-III. The origin of pedigrees with SMA in distant relatives is discussed.